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palsrc/palDfltin.c  view on Meta::CPAN

/*
*+
*  Name:
*     palDfltin

*  Purpose:
*     Convert free-format input into double precision floating point

*  Language:
*     Starlink ANSI C

*  Type of Module:
*     Library routine

*  Invocation:
*     void palDfltin( const char * string, int *nstrt,
*                     double *dreslt, int *jflag );

*  Arguments:
*     string = const char * (Given)
*        String containing number to be decoded.
*     nstrt = int * (Given and Returned)
*        Character number indicating where decoding should start.
*        On output its value is updated to be the location of the
*        possible next value. For compatibility with SLA the first
*        character is index 1.
*     dreslt = double * (Returned)
*        Result. Not updated when jflag=1.
*     jflag = int * (Returned)
*        status: -1 = -OK, 0 = +OK, 1 = null, 2 = error

*  Description:
*     Extracts a number from an input string starting at the specified
*     index.

*  Authors:
*     TIMJ: Tim Jenness (JAC, Hawaii)
*     {enter_new_authors_here}

*  Notes:
*     - Uses the strtod() system call to do the parsing. This may lead to
*       subtle differences when compared to the SLA/F parsing.
*     - All "D" characters are converted to "E" to handle fortran exponents.
*     - Commas are recognized as a special case and are skipped if one happens
*       to be the next character when updating nstrt. Additionally the output
*       nstrt position will skip past any trailing space.
*     - If no number can be found flag will be set to 1.
*     - If the number overflows or underflows jflag will be set to 2. For overflow
*       the returned result will have the value HUGE_VAL, for underflow it
*       will have the value 0.0.
*     - For compatiblity with SLA/F -0 will be returned as "0" with jflag == -1.
*     - Unlike slaDfltin a standalone "E" will return status 1 (could not find
*       a number) rather than 2 (bad number).

*  Implementation Status:
*     - The code is more robust if the C99 copysign() function is available.
*     This can recognize the -0.0 values returned by strtod. If copysign() is
*     missing we try to scan the string looking for minus signs.

*  History:
*     2012-03-08 (TIMJ):
*        Initial version based on strtod
*        Adapted with permission from the Fortran SLALIB library
*        although this is a completely distinct implementation of the SLA API.
*     2012-06-21 (TIMJ):
*        Provide a backup for missing copysign.
*     2012-06-22 (TIMJ):
*        Check __STDC_VERSION__
*     {enter_further_changes_here}

*  Copyright:
*     Copyright (C) 2012 Science and Technology Facilities Council.
*     All Rights Reserved.

*  Licence:
*     This program is free software; you can redistribute it and/or
*     modify it under the terms of the GNU General Public License as
*     published by the Free Software Foundation; either version 3 of
*     the License, or (at your option) any later version.
*
*     This program is distributed in the hope that it will be
*     useful, but WITHOUT ANY WARRANTY; without even the implied
*     warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
*     PURPOSE. See the GNU General Public License for more details.
*
*     You should have received a copy of the GNU General Public License
*     along with this program; if not, write to the Free Software
*     Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,